Monday, July 12, 2010

UK scientists show for the first time that high doses of caffeine directly increase muscle power and endurance during relatively low-intensity activities.

New research shows increased muscle performance in sub-maximal activities, which in humans can range from everyday activities to running a marathon.

With no current regulations in place, the scientists from Coventry University believe their findings may have implications for the use of caffeine in sport to improve performance.

The scientists presented their work at the Society for Experimental Biology Annual Meeting in Prague on Wednesday 30th June 2010.

"A very high dosage of caffeine, most likely achieved via tablets, powder or a concentrated liquid, is feasible and might prove attractive to a number of athletes wishing to improve their athletic performance", explains lead researcher, Dr Rob James.

"A small increase in performance via caffeine could mean the difference between a gold medal in the Olympics and an also-ran", he added.

Caffeine is not currently listed by the World Anti-Doping Agency (WADA) as a banned substance at any concentration in blood or urine samples. Before 2004 WADA did set a specific level over which athletes could be banned, but this restriction was removed.

Muscle activity is divided into maximal, where the muscles are pushed to full capacity such as in sprinting or weight lifting, and sub-maximal, which covers all other activities.

A member of the team, Jason Tallis, tested the effect of caffeine on both the power output and endurance of soleus muscles (lower leg muscle) in mice, under both maximal and sub-maximal activities.

He found that a caffeine dosage of 70 µM enhanced power output by ~6% during both types of activity. This effect in humans is likely to be very similar, according to the researchers.

"70 μM caffeine concentration is the absolute maximum that can normally achieved in the blood plasma of a human, however concentrations of 20-50 μM are not unusual in people with high caffeine intakes", explains Dr James.

Canadian scientists have identified which environmental stress conditions encourage pond snails to remember and which make them forget.

Predator scent enhanced the ability of pond snails (Lymnaea stagnalis) to form memory following training, whilst overcrowding and reduced calcium had a blocking effect.

"Understanding when stress blocks or enhances memory in a simple animal model may help elucidate the mechanisms in more complex animals such as humans", explained Dr Sarah Dalesman.

The researchers presented their work at the Society for Experimental Biology Annual Conference in Prague on Wednesday 30th June 2010.

Isolation had no effect on long-term memory (LTM) formation but when the snails were overcrowded or exposed to water with low calcium, which they need to grow their shells, their ability to form LTM was greatly reduced.

However, adding predatory crayfish scent into the water "super-sensitised" the snails, promoting LTM formation. It even reversed the effect of crowding and low-calcium, allowing the snails to remember their training.

"Predator scent seems to be able to rescue memory formation in the presence of all memory blocking stressors that we have investigated so far", explained Dr Sarah Dalesman.

The ability to form memory allows the pond snail to respond to experience during its lifetime and alter its behaviour appropriately. Dr Sarah Dalesman added, "Being able to remember which foods made them sick and which foods were alright will increase their probability of finding suitable food in the future"

Building on over 14 years of research at Professor Lukowiak's laboratory at the University of Calgary, Lymnaea stagnalis is an ideal candidate for memory tests, say the researchers.

They have large neurons, which allow them to pin-point exactly where in the brain memory is formed. They also have a simple set of behaviours making measuring memory formation a relatively simple task.

This work is currently ongoing and aims to develop an understanding of how stressors interact in Lymnaea stagnalis and to shed light on the effect of stress on memory formation in higher animals, including humans.

When oxygen levels in the water are low, instead of taking up oxygen directly through their skin, pond snails come up to the surface and breathe air through a rudimentary lung, opened to the atmosphere via the pneumostome.

During the "training", the scientists encouraged the snails to come up to the surface to breathe by artificially reducing the oxygen in the water, making it hypoxic.

When the snail opened its pneumostome at the surface, it was given a gentle poke with a wooden stick, causing it to close again. When this was repeated over a 2 hour training period, under normal conditions the snail remembered the poke and reduced the number of times it came up for air a day later, showing long term memory (LTM).

The scientists believe that the ability to remember unfamiliar environments, new predators and food sources is vital to the survival of the pond snail in the wild.

The flightless ostrich uses its wings very effectively in high-performance running and may provide valuable information about how its dinosaur ancestors moved, say researchers in Germany.

Once thought to be "evolutionary leftovers", new research has shown that ostriches in fact use their feathered forelimbs as sophisticated air-rudders and braking aids.

According to the researchers, wing-use and hindlimb function in ostriches may help palaeontologists in their quest to reconstruct locomotor techniques in bipedal (two-legged) dinosaurs.

The scientists presented their research at the Society for Experimental Biology Annual Conference in Prague on Thursday 1st July 2010.

Scientists have tended to disregard the use of wings in studies of ostrich locomotion, believing they were mainly for display and temperature-control purposes.

New, long-term observations of hand-raised ostriches, model calculations and air-stream experiments have shown that these flightless birds can efficiently channel aerodynamic forces and consistently use their wings during rapid breaking, turning and zigzag manoeuvres.

The results of this new study could mean that some of the largest and fastest-moving dinosaurs, such as the 8m long Gigantoraptor, also used feathered forelimbs for increased stability and manoeuvrability when moving at speed.

Palaeontologists have previously suggested that dinosaur forelimbs were used for "catching flying insects, grabbing branches or ripping out flesh from carcasses", explained lead researcher Dr Nina Schaller, who works with the Senckenberg Research Institute in Frankfurt and the University of Antwerp.

The scientists also found that a small intertarsal muscle, previously regarded as "rudimentary", actually plays a crucial role in ostrich locomotion.

If a comparable mechanism existed in extinct theropod dinosaurs that shared similar running styles and habitat, the energetic cost of carrying a heavy body would have been reduced, leaving the dinosaur more fuel to run longer and faster.

Dr Schaller hand-raised the ostriches for her research to ensure they could be studied in a natural, controlled environment which allowed them free space to perform without constraint.

"Ostriches can be very dangerous and can react with violent (even lethal) kicks and so it was crucial that we shared a deep level of mutual trust", she explained.

As well as the possible link to dinosaurs, Dr Schaller described similar wing uses in other modern flightless birds. "South American rheas execute rapid zigzagging as a means of escape and use their wings to maintain balance during these agile manoeuvres", she explained.

However, other relatives such as the Australian emu and the Cassowary have very small wings which they hold very tightly to their body and are not used in locomotion. "There seems to be a very direct link between wing-size and function", she added.

Future work will continue to examine ostrich wing characteristics and will hopefully establish additional links between ostrich and theropod dinosaur locomotion, say the researchers.

A study of the occurrence of fishes in the ocean's deepest reaches—the hadal zone, below 6000 meters—has provided evidence that some species of fishes are more numerous at such depths than experts had thought.

The authors of the study, which is published in the July/August issue of BioScience, observed 10 to 20 snailfish congregating at a depth of 7703 meters around a baited video lander in the Japan Trench. The observation period lasted only five hours, so the occurrence of so many snailfish, which were of the species Pseudoliparis amblystomopsis, was a surprise. Together with a critical review of past records of fishes found at great depths, the observations suggest, however, that few species of fishes survive in the darkness of the hadal zone.

Observations at such extreme depths—five times farther down than the oil leak in the Gulf of Mexico resulting from the Deepwater Horizon rig—are technically demanding and consequently rare. The researchers who conducted the new study, Toyonobu Fujii of the University of Aberdeen, United Kingdom, and four of his colleagues, used a free-fall lander that made video recordings of an illuminated patch of the sea floor for one minute every five minutes. This enabled the scientists to distinguish at least 10 individual fish and record their behavior, which was similar to the behavior of fishes observed in 1965 from a bathyscaphe at a depth of 7300 meters in the west Atlantic. The fishes observed by Fujii and colleagues fed on crustaceans that were attracted to the mackerel bait.

How deep fish can live has long been a controversial question. Previous records of fish supposedly captured at great depth are rare and mostly based on trawls, a technique that is subject to uncertainty about exactly when a fish entered the trawl net. Fujii and colleagues remark that "current understanding of the hadal environment is inadequate." They nonetheless suggest that fish may routinely occur far deeper than previously thought in ocean trenches, and that "liparids do appear to dominate and characterize hadal fish fauna." More research is necessary, the authors say, to learn how these fish populations interact with those in shallower water.

Even before the dawn of agriculture, people may have caused the planet to warm up, a new study suggests.

Mammoths used to roam modern-day Russia and North America, but are now extinct—and there's evidence that around 15,000 years ago, early hunters had a hand in wiping them out. A new study, accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union (AGU), argues that this die-off had the side effect of heating up the planet.

“A lot of people still think that people are unable to affect the climate even now, even when there are more than 6 billion people,” says the lead author of the study, Chris Doughty of the Carnegie Institution for Science in Stanford, California. The new results, however, “show that even when we had populations orders of magnitude smaller than we do now, we still had a big impact.”

In the new study, Doughty, Adam Wolf, and Chris Field—all at Carnegie Institution for Science—propose a scenario to explain how hunters could have triggered global warming.

First, mammoth populations began to drop—both because of natural climate change as the planet emerged from the last ice age, and because of human hunting. Normally, mammoths would have grazed down any birch that grew, so the area stayed a grassland. But if the mammoths vanished, the birch could spread. In the cold of the far north, these trees would be dwarfs, only about 2 meters (6 feet) tall. Nonetheless, they would dominate the grasses.

The trees would change the color of the landscape, making it much darker so it would absorb more of the Sun's heat, in turn heating up the air. This process would have added to natural climate change, making it harder for mammoths to cope, and helping the birch spread further.

To test how big of an effect this would have on climate, Field's team looked at ancient records of pollen, preserved in lake sediments from Alaska, Siberia, and the Yukon Territory, built up over thousands of years. They looked at pollen from birch trees (the genus Betula), since this is “a pioneer species that can rapidly colonize open ground following disturbance,” the study says. The researchers found that around 15,000 years ago—the same time that mammoth populations dropped, and that hunters arrived in the area—the amount of birch pollen started to rise quickly.

To estimate how much additional area the birch might have covered, they started with the way modern-day elephants affect their environment by eating plants and uprooting trees. If mammoths had effects on vegetation similar to those of modern elephants , then the fall of mammoths would have allowed birch trees to spread over several centuries, expanding from very few trees to covering about one-quarter of Siberia and Beringia—the land bridge between Asia and Alaska. In those places where there was dense vegetation to start with and where mammoths had lived, the main reason for the spread of birch trees was the demise of mammoths, the model suggests.

Another study, published last year, shows that “the mammoths went extinct, and that was followed by a drastic change in the vegetation,” rather than the other way around, Doughty says. “With the extinction of this keystone species, it would have some impact on the ecology and vegetation—and vegetation has a large impact on climate.”

Doughty and colleagues then used a climate simulation to estimate that this spread of birch trees would have warmed the whole planet more than 0.1 degrees Celsius (0.18 degrees Fahrenheit) over the course of several centuries. (In comparison, the planet has warmed about six times more during the past 150 years, largely because of people's greenhouse gas emissions.)

Only some portion—about one-quarter—of the spread of the birch trees would have been due to the mammoth extinctions, the researchers estimate. Natural climate change would have been responsible for the rest of the expansion of birch trees. Nonetheless, this suggests that when hunters helped finish off the mammoth, they could have caused some global warming.

In Siberia, Doughty says, “about 0.2 degrees C (0.36 degrees F) of regional warming is the part that is likely due to humans.”

Earlier research indicated that prehistoric farmers changed the climate by slashing and burning forests starting about 8,000 years ago, and when they introduced rice paddy farming about 5,000 years ago. This would suggest that the start of the so-called “Anthropocene”—a term used by some scientists to refer to the geological age when mankind began shaping the entire planet—should be dated to several thousand years ago.

However, Field and colleagues argue, the evidence of an even earlier man-made global climate impact suggests the Anthropocene could have started much earlier. Their results, they write, “suggest the human influence on climate began even earlier than previously believed, and that the onset of the Anthropocene should be extended back many thousands of years.”

This work was funded by the Carnegie Institution for Science and NASA.

Sweet news for those looking for new antibiotics: A new research published in the July 2010 print edition of the FASEB Journal (http://www.fasebj.org) explains for the first time how honey kills bacteria. Specifically, the research shows that bees make a protein that they add to the honey, called defensin-1, which could one day be used to treat burns and skin infections and to develop new drugs that could combat antibiotic-resistant infections.

"We have completely elucidated the molecular basis of the antibacterial activity of a single medical-grade honey, which contributes to the applicability of honey in medicine," said Sebastian A.J. Zaat, Ph.D., a researcher involved in the work from the Department of Medical Microbiology at the Academic Medical Center in Amsterdam. "Honey or isolated honey-derived components might be of great value for prevention and treatment of infections caused by antibiotic-resistant bacteria."

To make the discovery, Zaat and colleagues investigated the antibacterial activity of medical-grade honey in test tubes against a panel of antibiotic-resistant, disease-causing bacteria. They developed a method to selectively neutralize the known antibacterial factors in honey and determine their individual antibacterial contributions. Ultimately, researchers isolated the defensin-1 protein, which is part of the honey bee immune system and is added by bees to honey. After analysis, the scientists concluded that the vast majority of honey's antibacterial properties come from that protein. This information also sheds light on the inner workings of honey bee immune systems, which may one day help breeders create healthier and heartier honey bees.

"We've known for millennia that honey can be good for what ails us, but we haven't known how it works," said Gerald Weissmann, M.D., Editor-in-Chief of the FASEB Journal, "Now that we've extracted a potent antibacterial ingredient from honey, we can make it still more effective and take the sting out of bacterial infections."